->> While I have not tested my D850 yet with low light sports, it is supposed to be one-stop better than the D810 which I found to be really nice. The key though is proper color balance and proper exposure; do not underexpose because bringing it back to norm in post increases the noise making it worse than shooting at a higher ISO -- even when shooting RAW.

In the meantime, here's a tip for setting the correct white balance.

One of my anal quality controls is to start with a correct white balance in-camera, even when shooting RAW where it doesn’t matter. Doing so greatly cuts down on time consuming color corrections in post. Years ago I bought an expensive color meter to measure the Kelvin of where I’m shooting so I can set my camera(s) manually. Having a Kelvin readout in the camera would allow copying it to other cameras and write it down for return venue shoots. Now it is possible with the D850!

In the Playback menu there is an option for showing picture data when reviewing photos. The D800/D800E/D810 and others have it, showing it was shot in daylight, tungsten, flash and other modes. But now the D850 also displays the Kelvin number for images made using AUTO white balance. So instead of using the neutral color target in the ColorChecker Passport to do a PRE preset, shoot the target using AUTO white balance. Display the photo on your screen and go to the data screen. Next to the AUTO color balance setting is the actual Kelvin number it used.

Now, rather doing multiple PRE presets (one for each camera) which could vary, you can do one AUTO with the D850 and then manually dial in the Kelvin on all the cameras. This way they all match which makes doing varying color corrections in post unnecessary.

I think the camera is far superior at very high ISO than the 750. I haven't done any formal side-by-sides, but in real-world daily newspaper photography, it's kicking out better files - across the board - than the 750.

The D750 is still no slouch. I purchased the D850 to replace a D800 that now goes on the reserve backup list.

It seems comparable to when I made the jump from the D200 to the D300 to the D7000...

->> I can't advise on the D500, except that I was contemplating purchasing one before the D850 was announced.

I liked the specs on the D500, but didn't want to go back to the hassle of carrying one full frame camera and one crop camera. The 850 fit the bill as far as being newer technology, shooting large files and having a frame per second rate that sort of makes more sense for shooting sports.

->> Debra, I have the D500 and the D810. The D500 in low light is worse than the D810 by at least a stop, maybe more, but the AF is better, so I use it for sports more. So I assume the D850 would be even better, with similar AF of the D500.